Extracellular matrix and protein-based biomaterials emerge as attractive sources to produce scaffolds due to their great properties regarding biocompatibility and bioactivity. In addition, there are concerns regarding the use of animal-derived supplements in cell culture not only due to the risk of transmission of xenogeneic contaminants and antigens but also due to ethical issues associated with collection methods. Herein, a novel human protein-derived porous scaffold produced from platelet lysates (PL) as platform for xeno-free 3D cell culture has been proposed. Human PL are chemically modified with methacryloyl groups (PLMA) to make them photocrosslinkable and used as precursor material to produce PLMA-based sponges. The herein reported human-based sponges have highly tunable morphology and mechanical properties, with an internal porous structure and Young’s modulus dependent on the concentration of the polymer. Human adipose-derived stem cells (hASCs) are cultured on top of PLMA sponges to validate their use for 3D cell culture in xeno-free conditions. After 14 days hASCs remained viable, and results show that cells are able to proliferate during time even in the absence of animal-derived supplementation. This study reveals for the first time that such scaffolds can be promising platforms for culture of human cells avoiding the use of any animal-derived supplement.

Pulmonary fibrosis, characterized by progressive and irreversible lung tissue stiffening resulting in organ failure, is a growing health problem and belongs to the major causes of death worldwide. The pathological mechanisms of lung fibrosis are not fully understood; current pathogenic theories assume an impaired wound healing response to chronic lung injuries, in which the mechanical and chemical stimuli from the lung environment induces fibroblast activation. Currently, therapeutic options are severely limited, and lung transplantation remains the only effective treatment for patients in end-stage fibrotic diseases. Complex tridimensional (3D) lung platforms able to accurately recapitulate function, structure, and cell and matrix interactions found in fibrotic lung tissue, are therefore necessary to provide the means for understanding the pathological mechanisms and mediators involved in the fibrotic process. Of the vast array of biomaterials that have been used for Tissue Engineering (TE) applications, a major enthusiasm has been developed towards hydrogels: 3D water-swollen polymeric networks, that provide mechanical support to cells and allow for the diffusion of nutrients, waste, and oxygen. Hydrogels are particularly interesting to study lung diseases as they recapitulate the mechanical and viscoelastic properties found in load-bearing soft tissues like the lung. Natural-based hydrogels are appealing platforms as they are inherently biocompatible and bioactive. Platelet-rich plasma (PRP) and human platelet lysates (PL) provide interesting materials to create hydrogels as they are a source for human-derived growth factors (GF). However, they present poor mechanical properties and are easily degraded. Synthetic-derived hydrogels do not face these limitations, but they lack differentiative cues required for tissue development. Human methacryloyl platelet lysates (PLMA)- based hydrogels have been proposed as a biochemical and biomechanicalsuperior platform for cell culture purposes. These autologous, GF-rich, platforms are herein proposed as reliable 3D platforms to model the fibrotic lung. PLMA hydrogels recapitulated the pathological stiffness of the fibrotic lung and supported the viability of lung fibroblasts cells for at least 7 days in culture. Cells adopted different morphologies as matrix stiffness changed and were able to induce matrix deformations in PLMA hydrogels, suggesting the feasibility of this scaffold to induce a profibrotic phenotype in fibroblasts in 3D, therefore recapitulating the pathological remodeling of lung fibrosis.

Scaffolds for bone tissue regeneration should provide the right cues for stem cell adhesion and proliferation, but also lead to their osteogenic differentiation. Hydrogels of modified platelet lysates (PLMA) show the proper mechanical stability for cell encapsulation and contain essential bioactive molecules required for cell maintenance. We prepared a novel PLMA-based nanocomposite for bone repair and regeneration capable of releasing biofactors to induce osteogenic differentiation. Human bone marrow-derived mesenchymal stem cells (hBM-MSCs) were encapsulated in PLMA hydrogels containing bioactive mesoporous silica nanoparticles previously loaded with dexamethasone and functionalized with calcium and phosphate ions. After 21 d of culture, hBM-MSCs remained viable, presented a stretched morphology, and showed signs of osteogenic differentiation, namely the presence of significant amounts of alkaline phosphatase, bone morphogenic protein-2 and osteopontin, hydroxyapatite, and calcium nodules. Developed for the first time, PLMA/MSNCaPDex nanocomposites were able to guide the differentiation of hBM-MSCs without any other osteogenic supplementation.

To date, anticancer therapies with evidenced efficacy in preclinical models fail during clinical trials. The shortage of robust drug screening platforms that accurately predict patient’s response underlie these misleading results. To provide a reliable platform for tumor drug discovery, we herein propose a relevant humanized 3D osteosarcoma (OS) model exploring the potential of methacryloyl platelet lysates (PLMA)-based hydrogels to sustain spheroid growth and invasion. The architecture and synergistic cell-microenvironment interaction of an invading tumor was recapitulated encapsulating spheroids in PLMA hydrogels, alone or co-cultured with osteoblasts and mesenchymal stem cells. The stem cells alignment toward OS spheroid suggested that tumor cells chemotactically attracted the surrounding stromal cells, which supported tumor growth and invasion into the hydrogels. The exposure of established models to doxorubicin revealed an improved drug resistance of PLMA-based models, comparing with scaffold-free spheroids. The proposed OS models highlighted the feasibility of PLMA hydrogels to support tumor invasion and recapitulate tumor-stromal cell crosstalk, demonstrating the potential of this 3D platform for complex tumor modelling. STATEMENT OF SIGNIFICANCE: Cell invasion mechanisms involved in tumor progression have been recapitulated in the field of 3D in vitro modeling, leveraging the great advance in biomimetic materials. In line with the growing interest in human-derived biomaterials, the aim of this study is to explore for the first time the potential of methacryloyl platelet lysates (PLMA)-based hydrogels to develop a humanized 3D osteosarcoma model to assess tumor invasiveness and drug sensitivity. By co-culturing tumor spheroids with human osteoblasts and human mesenchymal stem cells, this study demonstrated the importance of the synergistic tumor cell-microenvironment interaction in tumor growth, invasion and drug resistance. The established 3D osteosarcoma model highlighted the feasibility of PLMA hydrogels as a relevant 3D platform for complex tumor modelling

Fundamental physiologic and pathologic phenomena such as wound healing and cancer metastasis are typically associated with the migration of cells through adjacent extracellular matrix. In recent years, advances in biomimetic materials have supported the progress in 3D cell culture and provided biomedical tools for the development of models to study spheroid invasiveness. Despite this, the exceptional biochemical and biomechanical properties of human-derived materials are poorly explored. Human methacryloyl platelet lysates (PLMA)-based hydrogels are herein proposed as reliable 3D platforms to sustain in vivo-like cell invasion mechanisms. A systematic analysis of spheroid viability, size, and invasiveness is performed in three biomimetic materials: PLMA hydrogels at three different concentrations, poly(ethylene glycol) diacrylate, and Matrigel. Results demonstrate that PLMA hydrogels perfectly support the recapitulation of the tumor invasion behavior of cancer cell lines (MG-63, SaOS-2, and A549) and human bone-marrow mesenchymal stem cell spheroids. The distinct invasiveness ability of each cell type is reflected in the PLMA hydrogels and, furthermore, different mechanical properties produce an altered invasive behavior. The herein presented human PLMA-based hydrogels could represent an opportunity to develop accurate cell invasiveness models and open up new possibilities for humanized and personalized high-throughput screening and validation of anticancer drugs.